Means for transforming direct current.



No. 757,228. PATENTED APR. 11, 1905. 0. P. STEINMETZ.

MEANS FOR TRANSPORMING DIRECT CURRENT.

APPLICATION FILED DEO.17,1903. RENEWED SEET.1,1904.

Wtnesses: lnverwtor: fizz 7W CharlesFZSteinmetz,

y ma hausted receptacle 2 of glass .or other suit- UNITED STATES,

Patented April 11, 1905.

PATENT OEEIcE.

CHARLES I. STEINMETZ, OF SCHENECTADY, NEW YORK, ASSIGNOR- TO GENERAL ELECTRIC COMPANY, A CORPORA"ION OF NEIV YORK.

MEANS FOR TRANSFORNIING DlRECT CURRENT.

SPECIFICATION forming part of Letters Patent No. 787,228, dated April 11, 1905. Application filed December 17, 1908. Renewed September 1,1904. Serial No. 223,004.

To a. "11/77/0721 it 717/11, concern: j

Be it known that I, CHAELEs P. STEIN- METZ, a citizen of the United States, residing l at Schenectady, county of Schenectady, and I State of New York, have invented certain i new and useful Improvements in Means for Transforming Direct Current, of which the l following is a specification.

My invention relates to the transformation of direct current into multiphase alternating current, and is embodied in an apparatus whereby this result is secured largely j through the instrumentality of a vapor electric device in which arcs are produced between the electrodes, one at least of which is of vaporizable material.

My invention includes various features of novelty, which I have pointed out with particularity in the appended claims.

As to the construction and mode of operation of my invention a better understanding thereof may be had by reference to the following description, taken in connection with the accompanying drawing, which illustrates one of the numerous embodiments which my invention may assume in practice.

In the drawing a source of direct current is indicated conventionally at 1. From this source is derived a direct current, which is to be transformed into multiphase alternating current. The vapor conductor, through the operation of which the transformation is largely effected, consists of a highlyexable material, provided with pockets for holding bodies of mercury 3 to 7, inclusive, constituting electrodes. In place of mercury any other suitable material maybe employed. The electrode 7 is located centrally with re spect to the other four electrodes and constitutes the cathode or negative electrode. It is connected through a leading-in conductor with the negative lead 8, extending from the source 1. The other electrodes, 3, 4, 5,

and 6, operate intermittently as anodes in a manner hereinafter to be described and are connected, respectively, with the terminals of two primary windings 9 and 10 of two transformers the corresponding secondaries the other primary, 10.

of which are indicated at 11 and 12. The diametrically-situated anodes are connected to the terminals of one primary and the other anodes to the terminals of the other primary-that is to say, the anodes 3 and 5 are connected to the terminals of the primary 9 and the anodes 4 and 6 to the terminals of The middle points of the two primaries 9 and 10 are joined by a conductor 13, and from this conductor connection is made through the lead 14 with the positive terminal of the direct current source 1..

In order to start up the apparatus, the receptacle 2 is tilted or shaken, so as to cause mercury to flow between the cathode 7 and one of the anodes, and is then moved back into its original position, so that the bridge of mercury thus formed is broken. A cur rent from the source 1 flowing between the cathode and one of the anodes when this bridge of mercury is formed then continues to flow by reason of the conducting-path formed by the are which follows the break in the mercury path. Suppose the arc to be formed between the anode 4 and the cathode 7. As soon as this are is formed it jumps to one of the adjacent anodes 3 and 5. It then jumps to the next anode beyond and continues thus to move rapidly around the cathode 7 in the center. The direction in which the are starts to move around the center is apparentlylargely a matter of chance. After the arc is started, however, it continues its rotation in the same direction and with a rapidity which depends to a considerable extent upon the size of the positive electrodes or anodes and their distances from the cathode. The shifting of the are from one anode to an adjacent anode seems to be due to the fact that as soon as the arc starts from one anode the heat thus generated produces an increasing resistance between the anode and the cathode until a point is reached where less resistance to current-flow exists between an adjacent anode and the cathode. The are then shifts to this adjacent anode and repeating the operation continues to shift from anode to anode in regular progression around the cathode. Suppose, for the sake of illustration, that the arc shifts in succession from anode 3 to anode 4, then to anode 5 and anode 6, and so around the circuit indefinitely. A pulsation of current is thus produced first in the lead 15, then in the lead 16, then in the lead 17, then in the lead 18, and so on. In producing these current pulsations current flows from the main 14 always in the same direction to the junction with the conductor 13, whence it passes in the direction of the arrows through the middle points of the primaries 9 and 10. Then the arc is passing from the anode 3 to the cathode, current is therefore flowing from the middle of the primary9 to the lead 15. When the arc shifts to the anode 4, current flows from the middle of the primary 10 to the main 18. hen the arc again shifts to the anode 5, the current flows from the middle of the primary 9 to the main 17. In the same way when the are shifts to the anode then current flows from the middle point of the primary 10 to the lead 18. As the are continues to shift from anode to anode the operations mentioned are repeated.

It will be observed that in each primary current first flows through one half of the winding, so as to produce a magnetizing force in one direction, and then through the other half of the winding, so as to produce a magnetizing force in the opposite direction. An alternating magnetomotive force is thus produced by each primary winding, which thereby generates in the corresponding secondary an alternating electromotive force. By reason, therefore, of the shifting of the arcs in the vapor conductor 2 a multiphase alternat ing current may be derived from the secondaries 11 and 12.

In order to render the flow of power in the directcurrent circuit more steady, and thus to fill up as much as possible the gaps or intervals during which no current, or at least a small current, is flowing in either of the primaries 9 and 10, I connect in series with the direct-current source an energy-storing device, such as an inductance-coil 19. This coil stores energy while the current is flowing directly from the source and discharges the energy in the form of current at such times as the current from the source tends to cease flowing or to fall in value. By the use of this energy storing and restoring device the alternating magnetizations produced in the primaries 9 and 10 approximate closely the effect of an ordinary alternating current.

The difference in phase between the currents produced by the secondaries 11 and 12 is due to the fact that the currents flowing in one primary, such as 9, occur at times half way between the occurrence of current flows or pulsations transmitted to the other primary, 10. In the arrangement shown the phase difference amounts to ninety degrees. It is evident, however, that instead of this quarter-phase arrangement I may select any other number of phases merely by increasing the number of transformers and their cooperating aondes accordingly. Thus with three transformers it would be evident that a six-phase relation would be produced.

Although I have described above one of the embodiments that my invention may assume in practice, it is evident that numerous modifications thereof and additions thereto may be made without departing from the spirit of my invention, for which reason I do not wish to be limited to the exact details shown and described.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

1. The combination of a plurality of transformer-windings, a vapor electric device having a cathode and a plurality of anodes, connections between the anodes and the terminals of said windings, a source of direct current, a connection from said source to said cathode, and another connection from said source to the middle points of said windings.

2. The combination of a source of direct current, a vapor electric device, and means cooperating with said source and said device for transforming direct current from said source into multiphase alternating current of an even number of phases.

3. The combination of an exhausted envelop, a cathode, a plurality of anodes arranged around said cathode, means for producing between said cathode and anodes an. are shifting in regular succession from anode to anode, and means for deriving from the pulsations of current passing to each anode a quarter-phase alternating current.

4:. The combination of a source of direct current, a vapor electric device having a cathode and a plurality of anodes, a winding having terminals connecting respectively to corresponding anodes, and a source of direct current connected between said cathode and. an intermediate point in said winding.

5. The combination of a source of direct current, a winding, and a vapor electric apparatus connected to said winding so as to produce current impulses flowing alternately in different parts of the winding.

In witness whereof I have hereunto set my hand this 15th day of December, 1903.

CHARLES P. STEIN Mlfl'l i.

Witnesses BENJAMIN B. HULL, HELEN ORFORD. 

